Fuel tank

ABSTRACT

A fuel tank for a motor vehicle having a chamber delimited by a wall and having an activated carbon filter located to ventilate the volume of the fuel chamber located above the level of fuel in the tank.

[0001] The invention relates to a fuel tank for a motor vehicle, havinga chamber which is delimited by a wall and is used to hold fuel andhaving an activated carbon filter which is provided for the purpose ofventilating the area of the chamber located above the fuel duringrefueling and/or during operation.

[0002] Fuel tanks of this type are in widespread use in modern motorvehicles and are known in practice. The activated carbon filter has ahousing which is made from the plastics polyamide or polypropylene andis partly reinforced with glass fibers and is connected to the chambervia a line which leads through the wall of the fuel tank.

[0003] A drawback of the known fuel tank is that fuel vapors can escapeinto the environment through the connections of the fuel tank and theactivated carbon filter, for example through leaks, diffusion orpermeation.

[0004] The invention is based on the problem of configuring a fuel tankof the type described in the introduction in such a way that fuel isparticularly reliably prevented from escaping.

[0005] According to the invention, this problem is solved through thefact that the activated carbon filter is arranged in the region of thechamber.

[0006] This configuration means that the fuel tank according to theinvention does not require any connecting lines between the chamber andthe activated carbon filter. Therefore, the connection between theactivated carbon filter and the chamber of the fuel tank does not haveany contact with the environment. Therefore, in the event of a leak oras a result of diffusion and permeation at the connection between theactivated carbon filter and the chamber, it is impossible for any fuelvapors to pass into the environment. The fuel tank according to theinvention particularly reliably prevents fuel from escaping into theenvironment. A further advantage of the fuel tank according to theinvention consists in the fact that it is particularly compact and has aparticularly small number of components which are to be fitted in themotor vehicle. Moreover, the invention makes it easy for the activatedcarbon filter to be integrated in the intended outer contour of the fueltank according to the invention.

[0007] Over prolonged periods, the housing materials used in modernactivated carbon filters are not able to withstand contact with liquidfuel. Therefore, consideration could be given to coating the housing ofthe activated carbon filter located inside the chamber or to making thishousing from a fuel-resistant material. However, this makes theactivated carbon filter expensive. However, according to an advantageousrefinement of the invention, the activated carbon filter can be producedat particularly low cost if it is arranged inside a compensation tankarranged in the chamber. This configuration allows the compensation tankto protect the activated carbon filter from contact with liquid fuel.

[0008] The fuel tank according to the invention is of particularlysimple design if a wall of the compensation tank has a molded formationfor holding the activated carbon filter.

[0009] According to another advantageous refinement of the invention, itis possible to particularly reliably prevent the activated carbon filterfrom being wetted with fuel by securing the compensation tank and/or theactivated carbon filter to the inner side of the upper wall of the fueltank.

[0010] A configuration in which the compensation tank and/or theactivated carbon filter forms a preassemblable structural unit with ashell part which forms an upper wall of the fuel tank makes the fueltank according to the invention particularly simple to assemble.

[0011] Assembly of the fuel tank according to the invention is furthersimplified if housing parts of the activated carbon filter and/or of thecompensation tank are joined by material-to-material bonding. Thisallows the components of the fuel tank to be, for example, weldedwithout difficulty.

[0012] According to another advantageous refinement of the invention,the number of connection points between the activated carbon filter andthe chamber can be kept particularly small if connections for vent lineswhich are guided into the region above the fuel in the chamber arearranged in housing parts of the activated carbon filter and/or of thecompensation tank.

[0013] The chamber requires a line which leads via the activated carbonfilter into the environment for the purpose of pressure equalization.According to another advantageous refinement of the invention, contactbetween liquid fuel and the connection of the line of the activatedcarbon filter which leads into the environment can be particularlyreliably avoided if a vent line which is intended for pressureequalization with the environment is guided through a common region ofthe wall of the chamber and of the compensation tank or of the activatedcarbon filter.

[0014] According to another advantageous refinement of the invention,assembly of the activated carbon filter in the compensation tank isfurther simplified if a housing part of the activated carbon filter isformed integrally with the compensation tank. This allows the activatedcarbon filter to be filled with activated carbon, welded closed andconnected to the ventilation system during assembly. Finally, thecompensation tank is welded closed.

[0015] According to another advantageous refinement of the invention,protection against wetting of the activated carbon filter is furtherincreased if a housing of the activated carbon filter is ofdouble-walled design.

[0016] According to another advantageous refinement of the invention,assembly of the activated carbon filter is further simplified if theactivated carbon filter has a cartridge comprising activated carbonwhich can be inserted into the compensation tank.

[0017] Connecting the activated carbon filter to the ventilation systemof the fuel tank according to the invention requires particularly littleassembly work if a line which is to be connected to the activated carbonfilter has a plug connection part.

[0018] The invention permits numerous embodiments. One of these isillustrated in the drawing and described below for the purpose offurther explaining the basic principle of the invention. In the drawing:

[0019]FIG. 1 diagrammatically depicts a fuel tank according to theinvention having an activated carbon filter arranged in a compensationtank,

[0020]FIG. 2 shows an activated carbon filter which is secured to anupper shell part of a further embodiment of the fuel tank according tothe invention,

[0021]FIG. 3 shows an activated carbon filter arranged in a moldedformation of a compensation tank,

[0022]FIG. 4 shows an activated carbon filter arranged in a base regionof a compensation tank.

[0023]FIG. 1 diagrammatically depicts a fuel tank in longitudinalsection, having a chamber 2 for holding fuel and having two shell parts3, 4. A compensation tank 5 arranged in the fuel tank 1 has a housingpart 6 of pot-shaped configuration and is secured to the upper of theshell parts 4 by material-to-material bonding. The upper shell part 4has an edge 7 for this purpose. The base region of the pot-shapedhousing part 6 of the compensation tank 5 is produced integrally with ahousing part 8 of an activated carbon filter 9. The housing part 8 isjoined to a cover 10 by material-to-material bonding. The activatedcarbon filter 9 has a cartridge 11 comprising activated carbon which hasbeen inserted into the housing part 8. Of course, the activated carbonfilter 9 can also be produced by activated carbon being introduced intothe housing part 8. Vent lines 12 lead into the compensation tank 5through the upper edge 7 of the shell part 4 of the fuel tank 1. Theactivated carbon filter 9 is likewise connected to the inner region ofthe compensation tank 5 via a vent line 13. A further vent line 14 leadsthrough a common region of the wall of the fuel tank 1 with thecompensation vessel 5 into the environment. As a result, for example inthe event of thermal expansion of the fuel in the chamber 2, gases canflow through the vent lines 12 into the compensation tank 5 and, fromthere, through the activated carbon filter 9 into the environment.Furthermore, a base valve 15 which ensures that liquid fuel which haspenetrated into the compensation tank 5 is returned to the chamber 2 isarranged in the base region of the compensation tank 5. On account ofthe position at which it is arranged, the activated carbon filter 9 inthe compensation tank 5 is substantially protected from contact withliquid fuel.

[0024]FIG. 2 shows a compensation tank 16 for the fuel tank 1 fromFIG. 1. This differs from that shown in FIG. 1 substantially through thefact that a cover 17 of an activated carbon filter 18 arranged insidethe compensation tank 16 has connections 19 and is connected to plugconnections 20 arranged in the upper region of the wall. Moreover theactivated carbon filter 18 has a double-walled housing 21.

[0025]FIG. 3 shows a compensation tank 22 which is intended to besecured in a fuel tank (not shown). The compensation tank 22 has twohousing parts 23, 24 which are welded to one another and, in the baseregion, a molded formation 25 for holding an activated carbon filter 26.A partition 27 for separating off the activated carbon filter 26 iswelded to the base region of the compensation tank 22. A connection 28for a vent line leads through the partition 27. This activated carbonfilter 26 too has a cartridge 29 inserted into the molded formation 25of the compensation tank 22. FIG. 4 shows a compensation tank 30 whichis of particularly simple design and in which an activated carbon filter31 is secured to the lower of two housing parts 32, 33 of thecompensation tank 30. Vent lines (not shown) can be connected to thecompensation tank 30 and the activated carbon filter 31.

1. A fuel tank for a motor vehicle, having a chamber which is delimitedby a wall and is used to hold fuel and having an activated carbon filterwhich is provided for the purpose of ventilating the area of the chamberlocated above the fuel during refueling and/or during operation,characterized in that the activated carbon filter (9, 18, 26, 31) isarranged in the region of the chamber (2).
 2. The fuel tank as claimedin claim 1, characterized in that the activated carbon filter (9, 18,26, 31) is arranged inside a compensation tank (5, 16, 22, 30) arrangedin the chamber (2).
 3. The fuel tank as claimed in claim 1 or 2,characterized in that a wall of the compensation tank (22) has a moldedformation (25) for holding the activated carbon filter (26).
 4. The fueltank as claimed in at least one of the preceding claims, characterizedby the compensation tank (5, 16, 22, 30) and/or the activated carbonfilter (9, 18, 26, 31) being secured to the inner side of the upper wallof the fuel tank (1).
 5. The fuel tank as claimed in at least one of thepreceding claims, characterized by the compensation tank (5, 16, 22, 30)and/or the activated carbon filter (9, 18, 26, 31) being designed as apreassemblable structural unit with a shell part (4) which forms anupper wall of the fuel tank (1).
 6. The fuel tank as claimed in at leastone of the preceding claims, characterized in that housing parts (6, 23,24, 32, 33) of the activated carbon filter (9, 18, 26, 31) and/or of thecompensation tank (5, 16, 22, 30) are joined to one another bymaterial-to-material bonding.
 7. The fuel tank as claimed in at leastone of the preceding claims, characterized in that connections (19, 28)for vent lines (12, 13) which are guided in the region above the fuel inthe chamber (2) are arranged in housing parts (6, 23, 24, 32, 33) of theactivated carbon filter (9, 18, 26, 31) and/or of the compensation tank(5, 16, 22, 30).
 8. The fuel tank as claimed in at least one of thepreceding claims, characterized in that a vent line (14) which isintended for pressure equalization with the environment is guidedthrough a common region of the wall of the chamber (2) and of thecompensation tank (5) or of the activated carbon filter (9).
 9. The fueltank as claimed in at least one of the preceding claims, characterizedin that a housing part (8, housing 21) of the activated carbon filter(9, 18, 26, 31) is produced integrally with the compensation tank (5,16, 22, 30).
 10. The fuel tank as claimed in at least one of thepreceding claims, characterized in that a housing (21) of the activatedcarbon filter (18) is of double-walled design.
 11. The fuel tank asclaimed in at least one of the preceding claims, characterized in thatthe activated carbon filter (9, 26) has a cartridge (11, 29) comprisingactivated carbon which can be inserted into the compensation tank (5,22).
 12. The fuel tank as claimed in at least one of the precedingclaims, characterized in that a line which is to be connected to theactivated carbon filter (18) has a plug connection part (20).